This invention relates to a system for measuring the electrical energy of the current flowing in at least one secondary electrical conductor, the secondary conductor being electrically connected to a primary electrical conductor, the primary conductor and the or each secondary conductor having substantially the same voltage, with this measurement system comprising:                a primary module comprising a radioelectric emitter and a measuring unit for measuring the voltage of the primary conductor,        at least one secondary module comprising a radioelectric receiver, an intensity sensor for measuring the intensity of the current flowing in the corresponding secondary conductor and a unit for calculating the electrical energy of said current flowing in the corresponding secondary conductor.        
This invention further relates to a unit for transforming an electrical current having a first alternating voltage into an electrical current having a second alternating voltage, this transformation unit comprising such a measurement system.
This invention further relates to a method for measuring electrical energy with such a measurement system.
It is known from document WO 2010/119332 A1 a measurement system of the aforementioned type. The measurement system comprises modules for measuring electrical energy, a database for storing measured values of the energy and a management module able to supply, to remote clients, information corresponding to the measured and collected values. The measurement modules are connected via radioelectric links to a communication gateway which is itself connected to a network. The database, the management module and the remote clients are also connected to the network. Each measurement module is able to measure the electrical energy of the current flowing in an electrical conductor. It comprises an intensity sensor, a processing unit able to calculate the electrical energy and a radioelectric emitter-receiver. Each measurement module is synchronised with the communication gateway via a clock.
However, such a measurement system is not very precise, with the calculation of the energy factor carried out through the detection of the maximums for the current and for the voltage and the calculation of the time that separate them. This system is also not very precise as it does not take into account in the calculation the energy produced by any harmonics present in the voltage and current signals. In addition, such a measurement system is relatively complex and expensive.